cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A258788 a(n) = [x^n] Product_{k=1..n} 1/(x^k*(1-x^k)).

Original entry on oeis.org

1, 1, 3, 12, 47, 192, 811, 3539, 15765, 71362, 327748, 1524081, 7161629, 33958506, 162312471, 781305581, 3784573140, 18435578714, 90261022638, 443956543235, 2192796266004, 10872208762458, 54095648185434, 270029668955605, 1351943521270155, 6787479872751732
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 10 2015

Keywords

Crossrefs

Programs

  • Maple
    T:=proc(n, k) option remember; `if`(n=0 or k=1, 1, T(n, k-1) + `if`(n
    				
  • Mathematica
    Table[SeriesCoefficient[1/Product[x^k*(1-x^k), {k, 1, n}], {x, 0, n}], {n, 0, 30}]
    Table[SeriesCoefficient[1/Product[1-x^k, {k, 1, n}], {x, 0, n*(n+3)/2}], {n, 0, 30}]

Formula

a(n) ~ c * d^n / n^2, where d = A258234 = 5.40087190411815415246609111910427005202943771019167057093170601448448... = r^2/(r-1), where r is the root of the equation polylog(2, 1-r) + log(r)^2 = 0, c = 2.578341962163260914344332458898614289944... .

A258798 a(n) = [x^n] Product_{k=1..n} (1+x^k)^3 / x^k.

Original entry on oeis.org

1, 3, 12, 62, 327, 1851, 10802, 64440, 391218, 2408001, 14989608, 94197594, 596756374, 3807010920, 24435261432, 157681777148, 1022391454116, 6657413851086, 43517229086467, 285447137446989, 1878287880309900, 12395149957521672, 82014499806039711
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 10 2015

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1+x^k)^3/x^k, {k, 1, n}], {x, 0, n}], {n, 0, 30}]
    Table[SeriesCoefficient[Product[1+x^k, {k, 1, n}]^3, {x, 0, n*(n+3)/2}], {n, 0, 30}]
    (* A program to compute the constant d *) (1+r)^3/r^2 /.FindRoot[-Pi^2/12 - Log[r]^2/3 + 1/2*Log[1+r]^2 + PolyLog[2,1/(1+r)] == 0, {r, E}, WorkingPrecision->100]

Formula

a(n) ~ c * d^n / n^(3/2), where d = 7.036711302278424796297167109247361745558645910729132828752853658917..., c = 2.3254811458... .

A258799 a(n) = [x^n] Product_{k=1..n} (1+x^k)^3 / x^(2*k).

Original entry on oeis.org

1, 1, 3, 13, 61, 324, 1800, 10340, 60969, 366486, 2237120, 13829487, 86394782, 544547651, 3458637273, 22113504345, 142212705879, 919294844898, 5969839457411, 38927450022860, 254776529381625, 1673102335692514, 11020847332241873, 72798664086854460
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 10 2015

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1+x^k)^3/x^(2*k), {k, 1, n}], {x, 0, n}], {n, 0, 30}]
    Table[SeriesCoefficient[Product[1+x^k, {k, 1, n}]^3, {x, 0, n*(n+2)}], {n, 0, 30}]
    (* A program to compute the constant d *) (1+r)^3/r /.FindRoot[Log[1+r]/Log[r] + (PolyLog[2,-r] + Pi^2/12) / Log[r]^2 == 1/6, {r, E}, WorkingPrecision->100]

Formula

a(n) ~ c * d^n / n^(3/2), where d = 7.036711302278424796297167109247361745558645910729132828752853658917..., c = 0.282321145891... .
Showing 1-3 of 3 results.